METAMAGNETIC TRANSITION OF UPT3 UNDER PRESSURE

The effect of hydrostatic pressure (P less-than-or-equal-to 5.1 kbar) on the metamagnetic transition of heavy-fermion UPt3 has been investigated by means of high-field magnetoresistance measurements (B less-than-or-equal-to 28 T) at a temperature of 2.0 K. The transition, which occurs at ambient pressure for a field directed in the hexagonal plane at B*=21 T, shifts upwards with pressure at a rate of 0.60 T/kbar. The deduced magnetic Gruneisen parameter, GAMMA(B)=-partial derivative lnB*/partial derivative lnV equals 59. The value for GAMMA(B) falls well within the range of values reported for the thermal Gruneisen parameter, 52 < GAMMA(T)=-partial derivative lnT*/partial derivative lnV<71, which verifies directly a close relation between the thermal and magnetic energy scales.